I know I'm supposed to add 243 to the other side but don't know what else to do. Divide maybe?

Thanks in advance.

-243+7x^2= 0 (reorder)
-243+243+7x^2 = 0+243 (add 243 to both sides)
7x^2=243 (Combine like terms)
x^2=34.71428571 (Divide each side by 7/simplify)
-34.71428571+x^2=34.71428571 +-34.71428571(reorder)
-34.71428571+x^2=0.00000000
Answer: The solution to this equation can not be determined.